<!DOCTYPE html>
<html>
	<head>
		<meta charset="utf-8">
		<title></title>
		<style>
			#div01
			{
				width: 50px;
				height: 50px;
				background-color: lightblue;
				position: absolute;
				top: 100px;
				left: 100px;
			}
		</style>
	</head>
	<body>
		<div id="div01">
			
		</div>
		<script>
			var moving = false;
			var posX;
			var posY;
			
			div01.onmousedown = function()
			{
				console.log("鼠标按下，准备开始移动")
				moving = true
				// 计算开始移动时 鼠标在块中的偏移位置
				posX = div01.offsetLeft - event.clientX;
				posY = div01.offsetTop - event.clientY;
			}
			div01.onmousedown = function()
			{
				if(moving)
				{
					div01.style.left = event.clientX+posX+"px";
					div01.style.top = event.clientY+posY+"px";
				}
			}
			div01.onmouseup = function()
			{
				moving = false;
			}
			
		</script>
	</body>
</html>
